1. Field of the Invention
The present invention relates to the field of switched telephony, and more particularly, to a method and system for providing a selectable continuous tone source from a service node to an end user.
2. Background of the Invention
Many Advanced Intelligence Network (AIN) telephone services use the capabilities of a service node (also referred to as a service circuit node) for intelligent call routing. In a typical routing scenario, the service node accepts an incoming call, places an outgoing call in response to the incoming call, and connects the incoming call to the outgoing call. Usually, once the calls are connected, the service node transfers the connected call to a service switching point to disencumber the service node (which is a more limited intelligent network resource). To transfer the connected call, the service node must place the incoming and outgoing calls on hold and transfer them to the service switching point with connection instructions, at which point the service switching point re-establishes the connection. This transfer typically occurs immediately after the service node has executed its intelligent routing functions and before any voice, data, or other communication is conducted over the completed connection.
The principal drawback to this routing strategy is a delay associated with the transfer from the service node to the service switching point. Depending on the particular type of AIN platform, the transfer may last up to three seconds. During this period, when both the incoming and outgoing calls are on hold, the customers on either side of the communication hear silence. As a result, the customers may become confused, mistakenly think the call has been disconnected, and hang up. This possibility is especially true for the calling party who has dialed a number only to experience an extended period of silence. Obviously, such a call switching deficiency severely detracts from any telephone service that uses this service node transfer and reduces the likelihood that a customer will subscribe to the service.
In addition to the call transfer problem, service nodes also put calls on hold to perform other functions, such as looking up data or communicating with other AIN components, e.g., service control points. An AIN service such as voicemail could present this situation. In such a case, the period on hold lasts as long as it takes the service node to process the information. Without connecting a music-on-hold source to the call during the processing, the customer hears silence while the service node has the call on hold.
Telephone service providers (hereinafter, referred to as xe2x80x9cTelcosxe2x80x9d) have attempted to address the on-hold silence by connecting the calls to a music-on-hold source during the transfer or processing period. Traditionally, the music-on-hold source is a standard audible ringing tone, source generated at a central office. FIG. 1 illustrates this architecture. Audible ringing is the typical sound heard after dialing a telephone number, consisting of two seconds of ringing followed by four seconds of silence. Unfortunately, the four seconds of silence is often greater than the on-hold period during a call transfer (approximately three seconds) or during a processing function (duration varies). Thus, even with audible ringing connected to the on-hold calls, the customer often hears just a portion of a ring or no ringing at all. In either case, the customer could still possibly be confused and hang up. Moreover, because it is the caller who is most likely to be confused, and not the subscriber (the called party), the Telco does not have the opportunity to explain this idiosyncrasy of the service to avoid the confusion. Thus, providing audible ringing for music-on-hold fails to solve the problem.
Telcos provide audible ringing through a physical connection to a standard ringing tone plant in a central office. The primary purpose of the tone plant is to provide the audible ringing heard after placing a call. The Telcos use the tone plant for music-on-hold only to take advantage of an existing resource. As an alternative to audible ringing, a Telco could develop a different ringing or tone pattern. However, the Telco would have to consult with an outside vendor, at considerable expense, to create a new type of ringing tone plant source. In addition, the Telco would have to create a new plant source for each type of tone source it desired.
Another drawback to using a tone source generated by the central office concerns the prevalence of equipment failures and the lack of alarming capabilities. Providing the tone source with the central office may require a physical connection to manufacturer discontinued equipment. Such discontinued equipment is prone to irreparable failure because of its age and the fact the manufacturer no longer produces the discontinued equipment or components of the equipment. Further compounding this reliability problem, if the central office tone source does fail, the central office has no means for alarming the customer about the failure. Thus, the customer would not be aware that the tone source is unavailable and would again be left with silence during the on-hold period.
Other solutions to on-hold silence present further drawbacks. Telcos can provide a music-on-hold tone source provisioned on customer premises equipment or on other tone generating equipment connected to the central office (e.g., radio playing). FIG. 2 shows the architecture for this solution. Although this solution allows a customer to customize the on-hold tone source, the architecture requires a permanent, dedicated line from the central office to the customer premises equipment. Because the line is dedicated, multiple customers cannot share the tone source. In addition, the customer is burdened with the expense and responsibility of continuously monitoring the tone source for failure situations.
The present invention is a system and method for providing an on-hold call with a selectable continuous tone source using a service node. The present invention comprises a service switching point (SSP) of a central office (CO) connected to a service node (SN) provisioned with a service logic program (SLP). Using the capabilities of the service node, the service logic program plays a continuous tone through a permanent trunk line connecting the service node to the service switching point. When the service switching point puts a call on hold, the service switching point connects the call through the permanent trunk line to the service logic program that is playing the continuous tone. As a result, the caller hears the continuous tone while the service switching point has the call on hold.
To enable users to select tones, the present invention further provides a dual tone multifrequency (DTMF) administrative interface on the service logic program of the service node. A customer can dial this interface, enter a passcode for access, and then choose between a variety of tone types such as a dial tone, a busy signal, a normal ring tone, a reorder signal (fast busy signal), a continuous busy signal, and a continuous ring tone.
The system architecture of the present invention uses a service switching point connected to a service node through at least two lines. The first line passes active calls between the service switching point and the service node, and is preferably a basic rate interface (BRI) connection. The second line is the permanent trunk line through which the continuous tone source is delivered, and is preferably a basic rate interface integrated service digital network (BRI/ISDN) connection. As would be apparent to one skilled in the art, the service switching point could be one or more service switching points located together or apart.
The present invention functions within the AIN network. AIN networks use a complex, high speed, high traffic volume data packet-switched messaging system to provide versatility in the handling of telephone calls. The Advanced Intelligent Network System is described in U.S. Pat. No. 5,701,301 and U.S. Pat. No. 5,838,774, which are hereby incorporated by reference.
The AIN enables telecommunications call control and database access from any computer or switching system connected to the Signaling System 7 (SS7) network. The Signaling System 7 network refers to the current implementation of the Common Channeling Interoffice Signaling control network used in the United States. The Advanced Intelligent Network (AIN) is a standard call control protocol that uses the SS7 network for message transport.
AIN infrastructures of the public switched telephone network include service switching points, service nodes, signal transfer points (STPs), and service control points (SCPs) with databases. The service control point is a computer that holds, accesses, and maintains the database and communicates with the service switching point in directing call routing. The database stores subscriber-specific information used by the network to route calls. The service switching point communicates with the service control point and queries the service control point for subscriber-specific instructions as to how calls should be completed. The signal transfer point is a packet switch that shuttles messages between the service control point and the service switching point. The service node is a smart termination that can assess incoming call information and make appropriate connections. In most implementations of a public switched telephone network, service control points, service switching points, and service nodes are also provided in redundant mated pairs to ensure network reliability.
With specific reference to the present invention, service nodes are intelligent components of the AIN network that read call information, determine call destinations, and issue instructions, while service switching points simply follow routing instructions and switch calls. The service node can be provisioned with a service logic program, which is an application that directs the actions of the service node.
Based on the above-described architecture, the present invention operates as follows. The service switching point connected to the service node receives an incoming call and forwards the call to the service node. The service node processes the call according to the particular AIN service that the service node is providing. The processing could include such actions as consulting a database for customer information, communicating with a service control point for routing information, or placing another call. In any case, if the action the service node must take will last a duration that justifies the use of a continuous tone source (typically, more than one or two seconds), the service node directs the service switching point to put the incoming call on hold. Once the call is on hold, the present invention uses the service switching point to connect the incoming call to the service logic program on the service node. Thus, while the service node is taking action, the caller placing the incoming call hears the continuous tone being played by the service logic program.
In addition to receiving incoming calls, the service node also places outgoing calls. Often, the service node places an outgoing call for the purpose of connecting the answered outgoing call with an incoming call. The present invention provides the same continuous tone source for these outgoing calls, when the outgoing calls are placed hold. Further, once a connection is made, the service node typically transfers the incoming and outgoing calls to the service switching points to free its resources for processing other calls. During this transfer period, when the incoming and outgoing calls are on hold, the present invention provides a continuous tone source to the calling party and the called party to avoid a confusing period of silence that gives the impression of a disconnected call.
In the preferred embodiment of the present invention, the trunk line between the service logic program and the service switching point provides a continuous tone source for a flexible call forwarding service. For this telephone service, the service node receives from the calling party an incoming call to the forwarding destination of the called party (subscriber). In response, the service node must determine the forwarding destination, determine how to route the call (including, for example, which outgoing port to use), set up appropriate billing and call identity information, place an outgoing call to the forwarding destination, connect the incoming call to the outgoing call, and transfer the connected calls to the service switching point to save the resources of the service node. During the transfer, which lasts from approximately one to three seconds, the service node places both the incoming and outgoing calls on hold. Without a music-on-hold source at this point the calling party and called party would hear silence. However, according to the present invention, the service switching point connects the incoming and outgoing calls to the service logic program while the service node is transferring the calls to the service switching point. Thus, the calling party and called party hear the continuous tone from the service logic program until the service node completes the transfer and the calls are permanently connected through the service switching point.
In another preferred embodiment of the present invention, the trunk line between the service logic program and the service switching point provides a continuous tone source for a simultaneous ring service. For this service, the service node receives an incoming call through a service switching point, consults a database to determine the group of phone numbers to simultaneously ring, places outgoing calls to each phone number in the group, and connects the incoming call to the outgoing call that is first answered. Like flexible call forwarding, once the incoming and outgoing calls are connected, the service node transfers the calls to the service switching point to save its resources. During this transfer, the present invention provides a continuous tone through the connection from the service logic program to the service switching point.
In another preferred embodiment, the present invention can also provide a continuous tone for a star code feature service. This service enables a customer to put an incoming call on hold at the central office while placing another outgoing call from the service node or using some other AIN service. If the outgoing call is answered and connected to the incoming call, the present invention provides a continuous tone through the connection from the service logic program to the service switching point, during transfer of the calls to a service switching point. If the service node is completing some other AIN service that involves a call that cannot receive an audible ringing tone from the central office, the present invention provides a continuous tone through the service logic program and service switching point connection.
Therefore, the present invention is a system and method for providing a continuous tone source to a call that has been placed on hold. The tone indicates that telephone routing is in process and eliminates the silence suggestive of a disconnected call. Further, the system and method places the burden of creating and maintaining the tone source on a Telco rather than the customer. Finally, the system and method is flexible such that a different tone source can be easily generated for particular situations, without having to consult with expensive outside vendors.
Accordingly, it is an object of the present invention to provide a continuous tone source for on-hold calls using a service node.
It is another object of the present invention to eliminate the customer confusion associated with a period of silence during service node call processing or call transfer.
It is another object of the present invention to provide a Telco with a means for creating and modifying continuous tone sources without having to consult with expensive outside vendors.
It is another object of the present invention to provide an administrative interface through which a customer can select a continuous tone to be heard when calls are put on hold.
It is another object of the present invention to provide a continuous tone source monitored by a Telco for alarm situations, thereby relieving the customer of the burden of maintaining a continuous tone source for on-hold calls or the burden of depending on a tone source generated by a central office subject to frequent failures of manufacturer discontinued equipment.
It is another object of the present invention to provide a continuous tone source that multiple customers can use.
These and other objects of the present invention are described in greater detail in the detailed description of the invention, the appended drawings, and the attached claims.